Field of the Invention (Technical Field)
Embodiments of the present invention relate to spark plugs wherein a portion of the spark gap comprises a surface gap and a portion comprise an air gap, thus forming a semi-surface gap. Embodiments of the present invention further comprise a semi-surface spark plug having a capacitor incorporated therein, thereby increasing the electrical current and thus the power of the spark during the streamer phase of the spark event and inducing the spark to project axially away from the spark plug and into an engine cylinder due to the Lorentz force. The additional increase in spark power creates a much larger flame kernel than is encountered in traditional spark plugs, thereby improving fuel ignition, enhancing completeness of fuel burn, and thus increasing the power output and fuel efficiency of the engine beyond that of a traditional spark plug.
Description of Related Art
While typical spark plug technology dates back to the early 1950's, recently there have been many attempts at creating higher capacitance in the spark plug or attaching a capacitor in parallel to existing spark plugs. Although these designs increase the discharge power of the spark, known designs are either inefficient or are complex and expensive. The present invention provides a simple and reliable method and apparatus whereby a capacitor is incorporated into a spark plug having a semi-surface gap.
U.S. Pat. No. 3,683,232; U.S. Pat. No. 1,148,106; and U.S. Pat. No. 4,751,430 discuss employing a capacitor or condenser to increase spark power. There is no disclosure as to the electrical size of the capacitor, which would determine the power of the discharge. Additionally, if the capacitor is of large enough capacitance, the voltage drop between the ignition transformer output and the spark gap could prevent gap ionization and spark creation.
U.S. Pat. No. 3,599,030 to Armstrong describes a surface-gap spark plug operating with an engine employing a capacitor discharge ignition system. Armstrong teaches that by using a surface gap design, coupled with a high tension, rapid-rise time discharge system, substantially all plug-maintenance issues can thus be avoided. Armstrong, however, fails to teach the use of a semi-surface plug or how to incorporate a capacitor into a plug, much less a capacitor which is automatically triggered. Because electrical resistance is lower across a surface than it is through an air-gap and because Armstrong merely teaches a surface-gap plug, the maximum voltage that Armstrong can create before its arc is initiated is thus much lower than that which would be possible if Armstrong formed all or at least a portion of the spark gap from an air gap. In addition, because the surface of the insulator which Armstrong uses acts as a heat sink to draw heat away from the arcing terminals, Armstrong is thus left to deal with carbon build ups on its outer electrode. Still further, because Armstrong's entire spark gap is formed from the surface of the insulator and because the breakdown voltage is thus much lower than what would be experienced if an air gap were used, the total peak voltage and current of the spark of Armstrong's plug is thus also lower. Because of the lower voltage and current, any resulting Lorentz force that Armstrong may experience is not sufficient to lift the spark off of the surface of the insulator and project it away from the spark plug and thus into the air/fuel mixture.
U.S. Pat. No. 4,549,114 claims to increase the energy of the main spark gap by incorporating into the body of the spark plug an auxiliary gap. The use of two spark gaps in a singular spark plug to ignite fuel in any internal combustion spark ignited engine that utilizes electronic processing to control fuel delivery and spark timing could prove fatal to the operation of the engine as the EMI/RFI emitted by the two spark gaps could cause the central processing unit to malfunction.
In U.S. Pat. No. 5,272,415, a capacitor is disclosed attached to a non-resistor spark plug. Capacitance is not disclosed and nowhere is there any mention of the electromagnetic and radio frequency interference created by the non-resistor spark plug, which if not properly shielded against EMI/RFI emissions, could cause the central processing unit to shut down or even cause permanent damage.
U.S. Pat. No. 5,514,314 discloses an increase in size of the spark by implementing a magnetic field in the area of the positive and negative electrodes of the spark plug. The invention also claims to create monolithic electrodes, integrated coils and capacitors but does not disclose the resistivity values of the monolithic conductive paths creating the various electrical components. Electrical components conductive paths are designed for resistivity values of 1.5-1.9 ohms/meter ensuring proper function. Any degradation of the paths by migration of the ceramic material inherent in the cermet ink reduces the efficacy and operation of the electrical device. In addition, there is also no mention of the voltage hold-off of the insulating medium separating oppositely charged conductive paths of the monolithic components. If standard ceramic material such as Alumina 86% is used for the spark plug insulating body, the dielectric strength, or voltage hold off is 200 volts/mil. The standard operating voltage spread for spark plugs in internal combustion spark ignited engines is from 5 Kv to 20 Kv with peaks of 40 Kv seen in late model automotive ignitions, which might not insulate the monolithic electrodes, integrated coils and capacitors against this level of voltage.
Although some conventional semi-surface gap plugs are known, such plugs have enjoyed only very limited use in internal combustion engines where a relatively constant engine speed is maintained. This is because semi-surface gap plugs are highly susceptible to fouling, which occurs in engines that encounter dynamic engine speeds. Because most engines, especially those in automobiles, routinely operate across a wide spectrum of engine speeds, known semi-surface gap plugs have been unable to provide desirable results and thus be adopted for use in such engines. One benefit of a pulsed semi-surface gap plug is that higher peak voltages are achievable over conventional plugs, thus imparting more ignition energy to the air/fuel mixture and thus increasing engine performance. There is therefore a present need for a semi-surface gap plug which can be used in dynamic speed engines.